BROTHERS: OTOLITH STUDIES 



53 



Fig. 23. Otolith primordia and cores. (A) SEM of single primordium and core in a french grunt (Haemulon flavolineatum) lapillus. (B) 

 Photomicrograph of single primordium and core in a mimic blenny {Labrisomus guppyi) sagitta. (C) Multiple primordia in the lapillus of a white 

 sucker {Caloslomus commersoni). (D) Multiple primordia in the sagitta of a seahorse (Hippocampus sp.). (E) Multiple primordia and cores in the 

 lapillus of a banded killifish (Fiindulus diaphamis). (F) SEM of multiple primordia and cores in the sagitta of a rainbow trout {Salmo gairdneri). 



ularly in the sagitta and lapillus) is a discrete, relatively ho- 

 mogeneous zone of calcified material usually delimited by a 

 distinct, thin, optically dense (matrix-rich) layer. This layer de- 

 fines the boundary of the core. In some cases, careful exami- 

 nation of the core may reveal diffuse, very faint, or extremely 



fine growth increments, however, they are easily distinguished 

 from the more distinct incremental growth pattern distal to the 

 core. Taxonomically related differences in core size, shape and 

 number generally parallel differences in the primordia. 

 The external morphology of larval fish otoliths is much less 



